Composite concrete

ABSTRACT

A method of manufacturing a projectile resistant concrete panel used in the construction of buildings including making a concrete panel and applying a composite laminate thereto. The method includes coupling together a plurality of frame segments so that a concrete frame is established. The frame has an interior space that forms a receiver for a concrete mixture. The frame is filled with the mixture so that the interior space is spanned by the mixture across the frame. The concrete mixture is cured to a rigid state so that the set concrete mixture is retained within the frame thereby forming a concrete panel. The concrete mixture may be a lightweight mixture having polystyrene pellets therein which improve upon the insulating characteristics of the panel. Building construction panels manufactured from the concrete mixture may be combined with high strength laminate coatings or layers. In this layered embodiment, the combination panel embodies sufficient strength characteristics to resist high wind storm conditions including strike tests of airborne objects. In another embodiment the lightweight concrete is utilized in a building block utilizable as a substitute for conventionally manufactured cinder blocks.

RELATED PATENT APPLICATIONS

This patent application claims priority to U.S. Pat. No. 5,737,896 filedSep. 5, 1996 entitled Lightweight Concrete and to U.S. ProvisionalApplication No. 60/050,630 filed Jun. 20, 1997 and entitled CompositeReinforced Concrete Panels. By this reference, the full disclosures,including the drawings, of U.S. patent application Ser. No. 08/711,414,U.S. Provisional Application No. 60/050,630 and PCT International PatentApplication Serial No. PCTIUS97/15659 are incorporated herein.

DESCRIPTION

1. Technical Field

This invention relates generally to lightweight concrete used in theconstruction of buildings and other structures. More particularly, itrelates to lightweight concrete within which a lightweight aggregate hasbeen incorporated. Examples of such aggregates include polystyrenepellets, fiberglass modules and/or organic matter such as cotton bollfragments produced as a byproduct of cotton ginning, ground wood and sawdust. Furthermore, the invention relates to reinforcement coatings orlaminate layers that are applied either to the exterior surface oracross the interior surface of a concrete panel used as a buildingconstruction component. Still further, this invention relates tosubstitute building blocks for use in place of cinder blocks that areconstructed from the lightweight concrete and can therefore have greaterlength dimensions and still be manually installed.

2. Background Art

Various compositions of concrete have long been used in the constructionindustry for building assorted structures. Concrete is a major componentin many load bearing supports maintained under compression. Examples ofsuch supports include pilings upon which buildings are supported, andfoundations and slabs that serve as bases for buildings. In other areas,concrete is used for sealing and providing structural integrity. Anexample of such use is the casing of water and oil wells.

The primary components of concrete are cement and aggregates that arefluidized with water and subsequently set into a rigid state. A primarydrawback associated with the use of conventional concrete mixtures isthat the resulting product is heavy and not suited for use in manyapplications because of its excessive weight. Many of the qualities ofconcrete, however, are highly advantageous and would be suitable in manyconstruction environments but for its relatively high weight. Examplesof such qualities are concrete's fire retardation, hardness andrigidity.

Previous attempts have been made to reduce the weight of concrete andachieve other beneficial characteristics. One such example is found inU.S. Pat. No. 5,352,390 issued to Hilton et al. on Oct. 4, 1994 forCementitious Compositions Containing Shredded Polystyrene Aggregate. Thedisclosure of that patent describes a fire-proofing composition whereina cementitious binder is utilized with a polystyrene aggregate. Theconcrete composition of Hilton may optionally include an air entrainingagent and other fibrous materials. This cementitious composition,however, is pump-sprayed upon typically metal building components. Thecompound's primary purpose is to lend fire-proofing qualities to thebuilding within which it is utilized.

In the Hilton disclosure It is explained that polystyrene panels are tobe appropriately shredded, with the resulting shredded matter being usedas aggregate in the concrete. The individual polystyrene particles ofthis shredded aggregate are "opened" to such a degree that the fluidizedcement mixture is able to invade the cellular body or interior of theparticle thereby weighing it down and facilitating its mixture into thecement binder. The Hilton disclosure is specific about the process forshredding the polystyrene into particles and its description of theresulting polystyrene aggregate; that aggregate having irregularlyshaped exterior surfaces with tears and ragged edges. The shreddingprocess opens a substantial number of the cells on the surface of thepolystyrene so that the cementitious binder is allowed to penetrate thecellular structure thereby providing a more integral mix between thebinder and the particle. It is further explained that if a sufficientnumber of cells are penetrated by the slurry, the buoyancy of theparticles is decreased to a point that the thickness of the slurryprevents the particles from floating therein. A certain degree offluidity and homogeneity is required to maintain the pumpability of theHilton composition. In strict contrast, however, it is explained thatnon-shredded beads segregate within the slurry, with the resultinglocalized concentrations of beads potentially clogging the pump, feedlines and spray nozzles of the applicator.

By opening the cells of the polystyrene particles as described in theHilton patent, the individual polystyrene particles become necessarilyweighted so that they mix into the pumpable slurry. This invasion of thefluid slurry into the particle, however, reduces its insulativequalities. Still further, it causes the resulting concrete to havesignificantly higher densities thereby increasing the weight of a givenvolume of concrete than if the cells of the polystyrene remained closed.Because of the limited application for the intention of the Hiltonpatent, that is, spraying the composition upon metal structuralcomponents in relatively thin layers, the increased weight and densitydoes not appear to cause ill-effects. When used in other applications,however, it has been found that such increases in density and weightprevent the realization of the true potential for using polystyreneaggregate.

Conventional concrete panels that have been used in buildingconstruction are known to resist compressive forces well, but notnecessarily forces that place the concrete portions of a panel intension. Because concrete often fails under tensile stresses, concretepanel building construction does not necessarily favorably withstandforces applied thereupon and perpendicular to the plane of the panel.For this reason, panels of conventional construction will not withstandsubstantial side forces, particularly impact forces. Such lateral forcesare often experienced in several storm conditions such as during atornado or hurricane. Without substantial reinforcement, generally inthe form of steel rebar or the like, concrete panel construction willnot necessarily be certifiable for use in storm prone locales.Accordingly, it is desirable to have the capability to provide concretepanels for building construction that not only are suitable forsupporting compressive forces, but that will also resist tensilestresses and sideward impacts that otherwise compromise the integrity ofthe building component.

The use of cinder blocks constructed from conventional concrete are wellknown in the building industry. Their use, however, had beensubstantially limited because there are few options for finishing abuilding constructed therefrom both interiorly and exteriorly of acinder block wall. Particularly, the hard face of the wall prevents thefastening of conventional finishing products such as exterior brickfascia and interior finishes such as dry wall or sheet rock. The primaryreason is that neither nails nor screws can be inserted into the hardsurfaced walls. Still further, like conventional brick erection, cinderblock construction is limited in height by the weight of the verticalrow stacks since mortar is used between the layers of blocks and theincreasing weight of a growing wall squeezes mortar from underlyinglayers. As a result, a cinder block wall must be built in stages, oftenrequiring idle time for those installing the wall and increasing boththe time for construction and the costs associated therewith.

DISCLOSURE OF THE INVENTION

This invention includes features and components that have been inventedand selected for their combined benefits and superior performance aslightweight concrete and concrete panels for use in buildingconstruction. Each of the individual components works in associationwith the others and are optimally mated for superior performance.

Referring now to specific embodiments of the lightweight concrete andseveral of its applications in the building construction business,additional benefits and advantageous features will be appreciated. Oneembodiment of the present invention is a method for preparing alightweight concrete. It includes mixing a slurry comprising water, acementing binder and a fine grain aggregate together. Polystyrenepellets are add-mixed to the slurry to form a substantially homogeneouslightweight concrete mixture.

In another embodiment, the lightweight concrete may be placed aboutconduits or pipes. The pipes may be located either above or belowground, but the use of the lightweight concrete as an encasement forpiping has been found to be of particular benefit in below groundsettings. The insulating lightweight concrete can be poured directlyaround the pipes and allowed to set thereabout. Alternatively, blocks orshells of the concrete can be formed having recesses that accommodateand receive one or more pipe lengths when installed thereupon.Complimentary halves may be mated together to form a complete enclosureabout a conduit. This application of the lightweight concrete findsutility where cooled and heated fluids are conveyed underground,especially for heating and air conditioning purposes.

In yet another embodiment, the lightweight concrete is used in themanufacture of cinder block-type building units. As a result of usingthe lightweight concrete, larger building units can be constructed thanthe conventional sixteen inch long cinder blocks of conventional design.The lighter weight permits the same handlers to manually lift andposition the block units in the construction process. Similar to cinderblocks, these improved building block units also have cylindricallyshaped voids that are vertically oriented and aligned one above theother in a wall's construction. By this alignment, continuous columnsare established from the bottom to the top of such a constructed wall.These columns may then be optionally reinforced by such means assimilarly vertically oriented rebar and then filled with eitherlightweight concrete or conventional weight concrete. In so doing, aconcrete column is established that extends vertically and continuouslythrough the constructed wall and permits that wall to be load bearing.

Because of the lightweight concrete's ability to be screwed and nailedinto, the surface of walls constructed from such building block unitsfacilitate the fastening of desired fascia thereto both interiorly andexteriorly. In an enhanced embodiment of such a block built wall,expanded metal sheeting is provided at either the interior or theexterior surface as reinforcement for restraining forces that applytensile stresses to the block built wall. A specific utilization hasbeen found in storm prone areas where the expanded metal sheeting actsas a shield to flying objects passing through the wall.

In the construction of a wall using these lightweight building blockunits, glue is substituted for the mortar that is used in conventionalcinder block construction. A thin layer of glue is used both between thewall and an underlying slab and elevated layers of blocks in theprogressively increasing layers of blocks as the wall is constructed. Byeliminating the need for a layer of mortar between the rows of blocks,there is no longer a concern about the weight of blocks above wet mortarsqueezing it from between the layers. This enhancement permits an entirewall to be built without delay in that it can be continuously stackedusing the thin layers of glue instead of the thicker and squeezablemortar layers.

Another embodiment of the present invention is a method for making alightweight concrete panel for use in a building's construction. Themethod includes coupling together a plurality of frame segments so thata frame for the concrete panel is established. The frame has an interiorspace that forms a receiver for a lightweight concrete mixture. Theframe is filled with a lightweight concrete mixture so that the interiorspace is spanned by the lightweight concrete mixture across the frame.The lightweight concrete mixture is cured to a rigid state so that theset lightweight concrete mixture is retained within the frame therebyforming a lightweight concrete panel.

In yet another embodiment, this invention provides a method forconstructing a building using lightweight concrete panels. A pluralityof lightweight concrete panels are formed, each bounded at leastpartially about a perimeter by a concrete frame. A building foundationis provided with a recess formed about a perimeter thereof, the recesshaving a width approximately equal to a thickness of the lightweightconcrete panels. At least a portion of the plurality of lightweightconcrete panels are up-ended into the recess and adjacent lightweightconcrete panels are coupled together so that a substantially uprightwall of a building is formed about at least a portion of a perimeter ofthe foundation.

In still another embodiment, this invention includes the manufacture ofconcrete panels made from lightweight concrete, regular concrete and/orhigh density concrete and used in the construction of buildings designedto withstand storm conditions that may be experienced in tornadoes andhurricanes. The ability to resist impact and tensile stresses within thepanel is owed to both a steel mesh reinforcement encased within thepanel's interior, as well as a surface coating of a high impactresistant material such as the aramid resin sold by E. I. Du Pont deNemours and Company under the trademark KEVLAR. The exterior layer ofthe high strength material may be instead be placed as an interior layerwithin the concrete panel. It is expected, however, that use of the highstrength material coating layer at the exterior surface of the panelpermits the resistance of impact forces exerted upon a building therebypreventing destructive tensile stress from being introduced into thepanel's body. In this manner, the compressive strengths of the concretepanel may be exploited, together with benefits realized from highstrength, but more expensive building materials such as the aramid resinsold by E. I. Du Pont de Nemours and Company under the trademark KEVLAR.Through the combination of the several layers of different constructionmaterials described herein, panels having significantly high strengthmay be manufactured for use in building construction that withstand testprocedures required for use in storm prone localities.

Among others, the present invention includes the discovery of alightweight concrete mixture that is achieved by add-mixingsubstantially closed body polystyrene pellets to a specially preparedconcrete slurry. One aspect of the invention is the unique methodutilized in the mixing process of the lightweight concrete. Anotheraspect is a unique application for the new mixture wherein modularpanels are constructed for use in the erection of both commercial andresidential buildings.

The primary benefit of the concrete composition itself is itslightweight nature. By incorporating the polystyrene particles, theweight of the resulting concrete is substantially reduced thereby makingthe composition utilizable in many more structural applications thanpreviously possible. Not only is this concrete composition lightweight,but it also has other beneficial qualities such as flame retardation andinsulative capacities as a construction material. It acts as aninsulator because of the polystyrene pellets that are entrainedthroughout the mixture; each of which encapsulate air pockets that areinefficient conductors of heat and therefore good insulators.

This improved composition that produces lightweight concrete isutilizable in environments other than building construction. It iscontemplated that such a lightweight concrete may be advantageously usedin the casing of subterranean wells, such as water wells and oil wells.In the process of casing a well, the concrete is pumped downwardadjacent to the well's piping and then normally it is pumped at leastpartially back-up about an opposite side of the tubular piping. Theheavier the concrete, the more difficult it is to pump the fluidizedmixture down along the casing; however, it is especially difficult topump heavier mixtures back up along the conduit. It is also contemplatedthat the lightweight concrete of the present invention may beadvantageously employed in any other environment wherein the resultingweight of the constructed element is a design criteria and theproperties of this new composition otherwise satisfy the functionalrequirements of the end product.

It is contemplated that other types of lightweight aggregate may be usedin place of the polystyrene or Styrofoam pellets. Fiberglass may beadded to the mixture for providing additional strength to the resultingconcrete while maintaining its lightweight nature. Still further, it iscontemplated that organic matter having a low density such as cottonburrs may be employed as an aggregate for similar effects.

A particularly beneficial use of the lightweight concrete mixture hasbeen discovered in the manufacture of lightweight construction panelsused in the building of both exterior and interior walls of a building.As previously described, the lightweight concrete provides enhancedinsulative capabilities that eliminate the need for additionalinsolation and other associated building materials in many instances.This composition is not only less expensive than other more conventionalconstruction modes, but it also permits more rapid on-site erection of abuilding.

In a primary embodiment, these panels are constructed within a frame ofC-shaped purlins that, when assembled, resemble a picture frame. Thedepth of these frames may be varied in order to alter the thickness ofthe resulting wall. Obviously, the thicker the wall, the heavier it willbe, but it will also increase that wall's insulative capabilities andresistance to penetration. Therefore, by appropriately selecting theexterior framing of the panel, functional characteristics of theresulting wall may be varied and altered.

The framework of the panel provides ready means for attaching panels oneto the other when forming a wall. In most instances, the C-purlin willbe constructed from weldable steel making it possible to form asubstantially contiguous wall out of adjacent panels. Other structuralcomponents may also be advantageously constructed from the lightweightconcrete such as foundations wherein the underlying soil cannot supportthe extreme weight of a conventionally paved slab. Furthermore, it isespecially useful in upper-floor slabs wherein weight is of the utmostimportance and usually a design criteria.

Because of the panel's lightweight nature and relative high strength,this structural configuration is particularly advantageous for use as asafety shield in natural disasters such as hurricanes, tornadoes andearthquakes. Because of the present invention's reduced weight, abuilding constructed therefrom will be less susceptible to the effectsof an earthquake because of the reduced mass in the upper floors. Thesepanels may also be reinforced with either conventional rebar that iswelded within the panel's frame or with a plastic reinforcing mesh thatis connected within the frame and which increases the tensile strengthof the panels. With appropriate reinforcement, these lightweightconcrete panels can withstand almost all wind forces and can resist andprovide adequate shields against the penetration of most flying debris.

Among those benefits and improvements that have been disclosed, otherobjects and advantages of this invention will become apparent from thefollowing description taken in conjunction with the accompanyingdrawings. The drawings constitute a part of this specification andinclude exemplary embodiments of the present invention and illustratevarious objects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram illustrating the process of mixing thelightweight concrete mixture, constructing the lightweight concretepanels from that mixture, and ultimately erecting buildings using thelightweight concrete panels as structural components.

FIG. 2 is a perspective view of one of the manufactured lightweightconcrete panels.

FIG. 3 is a cross-sectional view of a portion of a panel illustrating aC-shaped frame segment with a fortifying reinforcement connected thereinand with lightweight concrete solidified thereabout.

FIG. 4 is a partial cut-away showing at least portions of a buildingerected according to the present invention.

FIG. 5 is a cross-sectional view showing a framed lightweight concretepanel erected and anchored upon a building's foundation.

FIG. 6 is a cross-sectional view of a polystyrene pellet having agas-filled cellular interior and exterior skin.

FIG. 7 is a schematic view of a laminate building construction panelincluding a high strength exterior layer joined to a concrete panel thatare together suitable for use in building construction.

FIG. 8 is perspective view of three building block units arranged sothat the hollowed columns are vertically aligned with a rebar insertlocated within one of such columns.

MODE(S) FOR CARRYING OUT THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale, somefeatures may be exaggerated to show details of particular components.Therefore, specific structural and functional details disclosed hereinare not to be interpreted as limiting, but merely as a basis for theclaims and as a representative basis for teaching one skilled in the artto variously employ the present invention.

Certain terminology will be used in the following description forconvenience and reference only and not for purposes of limitation. Forexample, the words "rightwardly", "leftwardly", "upwardly" and"downwardly" will refer to directions in the drawings to which referenceis made. The words "inwardly" and "outwardly" refer to directions towardand away from, respectively, the geometric center of the structure beingreferred to. This terminology includes these words, specificallymentioned derivatives thereof, and words of similar import.

Furthermore, elements may be recited as being "coupled"; thisterminology's use anticipates elements being connected together in sucha way that there may be other components interstitially located betweenthe specified elements, and that the elements may be connected in fixedor movable relation one to the other. Certain components may bedescribed as being adjacent to one another. In these instances, it isexpected that a relationship so described shall be interpreted to meanthat the components are located proximate to one another, but notnecessarily in contact with each other. Normally there will be anabsence of other components positioned therebetween, but this is not arequirement. Still further, some structural relationships ororientations may be designated with the word "substantially". In thosecases, it is meant that the relationship or orientation is as described,with allowances for variations that do not effect the cooperation of theso described component or components.

The present invention comprises a lightweight concrete mixture 10 thathas been discovered to have unique characteristics and applications inits set or hardened state. Furthermore, several particularlyadvantageous applications have also been discovered that permit theemployment of the lightweight concrete mixture 10 in ways that arespecially beneficial to the building construction industry.

As previously described, it is known to mix shredded polystyrene into asoft cement mixture. To assure that the shredded polystyrene mixed intothe cement, however, the cells of the polystyrene pieces previously wereopened to allow the cement to infuse therein causing the polystyreneparticles to have a density more similar to the cement mixture so thatthe two would mix. The present invention includes the discovery of amethod by which polystyrene pellets 25 can be add-mixed to a slurry 15that is made up of the same primary components that comprise mostconcrete mixtures. Those components that are typically mixed together toform a liquefied concrete slurry 15 are water 17, a cementing binder 20and a fine grain aggregate 23. In most situations, the cementing binder20 is portland cement and the fine grain aggregate 23 is typically sand.It has also been found advantageous to add a quantity of fly and/orbottom ash to the cement mixture. The fly ash is a common component ofconcrete mixes and is typically obtained as a waste product of coalburning processes. The fly ash has beneficial aspects because of itsvery fine particulate size. Because of this very small particulate size,the coal ash fills voids that would otherwise remain open therebycompromising the strength of the resulting set concrete structure. Fibermesh may also be optionally added to the concrete mixture that consistsof chopped, stranded fiberglass which is blended directly into theconcrete prior to its utilization in a buildings construction. Thefiberglass interweaves and provides tensile strength to the resultingstructure and may be used to eliminate the use of wire or other rebartype reinforcement.

To achieve the advantageous qualities described herein, it has beendiscovered that the polystyrene pellets 25 must resist, instead ofaccommodate, the infusion of the other components of the slurry 15.Therefore, it is important that each polystyrene pellet 25 be a discreteunit that acts as a sealed air pocket or pouch. Such polystyrene pellets25 have heretofore not been utilized in such a manner for producing alightweight concrete mixture 10. Each polystyrene pellet 25 has agas-filled cellular interior 30 that is encased within an exterior skin35. The skin 35 is substantially impervious to fluid permeation. Assuch, the fluid components of the concrete slurry 15 are prevented frominvading the cells of the polystyrene pellets' 25 interior 30. In thismanner, the qualities enhanced by the gas-filled nature of thepolystyrene pellets 25 are retained and prevented from being compromisedas in the situation where those same cells would be purposefully openedby a shredding process that is used as a means by which the thoroughmixing of polystyrene is achieved in a concrete mixture.

It has been discovered that polystyrene pellets 25 utilized in thisinvention are most advantageously sized to have diameters falling withina range between one-eighth of an inch and one-quarter of an inch. Suchsized pellets 25 are readily achieved by pulling polystyrene early fromthe puffing process before complete expansion is achieved. By usingthese pre-puff polystyrene pellets 25 having sizes in the prescribedrange, fastenability is provided. Specifically, with the size of voidsestablished by the pellet' presence, typical wood screws and nails canpierce into the hardened lightweight concrete structures and berestrained therein and prevented from unintentionally pulling out. Thisis achieved because the voids are easily pierced by the nails and screwswhich are restrained by the engaged concrete portions that surround andestablish the side surfaces of such voids.

Because of the pellets' 25 relative lightweight in comparison to theconcrete slurry 15, it has been discovered that mechanicalcharacteristics must be imparted to the slurry 15 to assure that, whenthe polystyrene pellets 25 are add-mixed thereto, they blendhomogeneously throughout the slurry 15 to create the desired lightweightconcrete mixture 10. In order to achieve such a homogenous mixing, ithas been found of primary importance to raise the viscosity of theslurry 15 so that when the polystyrene pellets 25 are added they areheld within the slurry 15 and not permitted to segregate therefrom by afloating action. In practice, this increased viscosity is achieved bycarefully monitoring the proportions of the components that make up theslurry 15. Specifically, the amount of water normally added to establisha typical concrete mixture is reduced. By such a reduction, the mixtureis dryer and therefor more viscous and resistant to flow. This featureaccounts for the resistance of the mixture 10 to the floating of thepolystyrene pellets 25 therefrom. While the exact proportions of thecomponents to be so mixed together into the lightweight concrete mixture10 are not absolutely critical, it has been found to be advantageous forthe volumetric proportions of the components of the mixture 10 to beapproximately one part portland cement 20, approximately two parts sand23, and approximately five parts polystyrene pellets 25.

Prior to the introduction of the polystyrene pellets 25, the consistencyof the concrete slurry 15 is adjusted by controlling the amount of wateradded thereto. In order to achieve the desired effects described herein,that amount of water is minimized thereby raising the viscosity of theslurry 15 and even establishing a tacky quality that causes the slurry15 to adhere to the dry polystyrene pellets 25 when added thereto. Bycontinued mixing of the lightweight concrete mixture 10, the polystyrenepellets 25 are retained homogeneously therein despite a wide disparitybetween those pellets' 25 relatively low density and the substantiallygreater density of the slurry 15 to which those pellets' 25 have beenadded.

A particularly advantageous application for the employment of such alightweight concrete mixture 10 as has been described immediately aboveis the manufacture of lightweight concrete panels 40 that can be used aspre-formed structural components in the building industry. Suchlightweight concrete panels 40 have many beneficial characteristicsresulting because the lightweight mixture 10 is used in theirmanufacture. Among those benefits are increased insulativecharacteristics, as well as a reduction in the weight of such aconstructed panel 40 in comparison to a similarly configured anddimensioned panel made from a conventional concrete mixture. Theseconcrete panels 40 are constructed so that they may be utilized as apreviously fabricated (commonly abbreviated as "pre-fab") component thatmay be manufactured at one location and transported to a building site.This remote manufacture is a highly desirable capability because theenvironment within which the panels 40 are constructed is more easilycontrolled within a factory setting than at an actual building site.Furthermore, by constructing the panels 40 in a factory, the buildingmaterials may be centrally located as can the mixing machinery.

In the manufacturing process of a concrete panel 40 according to thepresent invention, a concrete frame 50 is initially constructed. In apreferred embodiment, the concrete frame 50 resembles a picture frame inthat it is rectangularly shaped with a concrete body of the panel 40contained within that frame 50. Such a frame 50 is preferablyconstructed from frame segments 45 that are cut from C-shaped purlins65. While it is not absolutely necessary that the segments 45 be joinedat right angles at the corners, it is preferred so that a welded seammay be had at such a corner for structural integrity of the frame 50.The C-shaped purlin 65 is configured so that an interior space isestablished within the segment itself. Each segment is oriented so thatan open side of the purlin 65 opens toward an interior space 55 of theframe 50. The interior space 55 establishes and forms a receiver withinwhich the lightweight concrete mixture 10 is deposited and retained. Ina preferred embodiment, fortifying reinforcements 60 are coupled withinthe frame 50 for adding structural strength to the panel 40 after theconcrete mixture 10 has set. It is contemplated that the reinforcements60 may take the form of conventional metal rebar that is welded into theinterior space 55 of the frame 50, or alternatively it may comprise aplastic mesh 60 which is also commonly used in concrete construction forproviding reinforcement against tensile stresses experienced by thepanel 40. These reinforcements 60 are required because the concreteitself is primarily capable of supporting compression forces while thereinforcement 60 resists tensile stresses that may otherwise compromisethe integrity of the panel 40. It is common for such mesh to bemanufactured from plastic or other material different than metal andtherefore it may be required that such reinforcement be connected to theframe 50 in ways other than welding such as adhesives or mechanicalcouplings.

It is highly desired that the lightweight concrete panels 40 constructedaccording to the present invention be readily accepted by theconstruction industry and easily integrated into current buildingdesigns. It has been discovered that such panels 40 may beadvantageously dimensioned to four foot widths by eight foot heights. Inthis manner, the panels 40 are similarly sized to conventional plywoodsheeting and gypsum dry wall or sheetrock that are readily available andcommonly used by building designers and construction workers who arefamiliar and comfortable with such dimensions. Like other manufacturedcomponents, panels 40 of variable sizes may be easily constructed merelyby varying the dimensions of the concrete frame 50 within which thepanel 40 is constructed.

Each frame 50 is constructed so that the frame segments 45 thatestablish the perimeter of the panel 40 are substantially maintainedwithin a single plane. That is to say, when the frame 50 is laid upon aflat surface, it lays in substantially continuous contact therewith.This is important in that the panels 40 are constructed by positioningsuch a planar frame 50 on plastic sheeting 70 laying upon a flat surfaceso that the interior space 55 may be filled with the lightweightconcrete mixture 10. The sheeting 70 may be constructed from othermaterial than plastic that is stick-resistant with respect to thelightweight concrete mixture 10. What is important is that after thepanel has solidified and the concrete hardened that it be easily removedfrom that sheeting 70 without undue adhesion.

Alternatively, a different type of sheeting 70 may be used that doesadhere to the concrete mixture 10 and as a result forms an encasement atone side of the panel 40. Such a configuration finds application whereit is advantageous that the panel 40 be water-tight or otherwiseresistant to moisture passing therethrough. Instances of suchapplication might be exterior walls of buildings that are to beweather-tight. In this case, what the sheet 70 upon which the panel 40is constructed must do is assure that the panel 40 may be easily raisedfrom the flat surface upon which the panel 40 was originally poured, butmay remain attached to the surface of the panel 40.

The panel 40 itself is constructed by placing the frame 50 upon thesheeting 70 which covers a flat surface. The appropriately mixedlightweight concrete mixture 10 is then poured into the frame 50 so thatit is completely filled. The mixture 10 in frame 50 may be appropriatelyagitated to assure that large air pockets and voids have been eliminatedfrom the high viscosity concrete mixture 10. Excessive agitation,however, should be prevented because of the floating tendencies of thepolystyrene pellets 25 within the lightweight concrete mixture 10,despite the mixture's 10 relatively high viscosity. The top surface ofthe panel 40 opposite the lower surface is smoothed so that the top andbottom surfaces are established parallel one to the other.

After the panel 40 has been accordingly formed, the concrete mixture 10is permitted to solidify and harden into a rigid panel 40 that may beutilized as a building construction component. Because the curing andsetting process of the panel 40 preferably takes place within a factorysetting, the conditions for curing may be controlled and optimized. Suchconditions include hydration which is the continuous application ofwater that is required in the curing process.

The characteristics of the panel 40 may be varied by selectingdifferently sized C-shaped purlins 65 for the construction of the frame50. The depth of such purlins 65 vary widely and are contemplated tooptimally range between three and ten inches. The depth measurements mayvary widely, however, based on the in-use criteria for the panel 40.

The panels 40 are commonly employed in an up-ended configuration to formboth interior and exterior walls 90 of a building 77. Because of theunique combination of the several constituent components that make upthe lightweight concrete mixture 10 and ultimately the lightweightconcrete panel 40, particularly advantageous qualities are achievedwithin the panel 40 with respect to such building's 77 construction.Because of the high polystyrene pellet 25 composition, the qualities ofthe panel 40 are substantially altered from a panel constructed fromconventional concrete mixtures. It has been found that panels 40constructed according to the present invention may be manipulatedsimilarly to panels constructed from sheetrock and wood. Morespecifically, these lightweight concrete panels 40 may be sawed byconventional means, as well as nailed and screwed. These featuresprovide substantial improvements over conventionally constructedconcrete panels and facilitate their customability at the building siteby the personnel commonly employed for their erection.

Because of the wide array of environments within which such panels 40may be utilized, it may be more advantageous to have the C-shapedpurlins 65 constructed from a material such as plastic, rather thanmetal, that may also be easily cut like the concrete body of the panel40. Such a plastic composition of the C-shaped framing purlin 65 isconsidered optional because in many construction applications a metalframe 50 will be more desirable because it facilitates a weld connectionbetween such panels 40 in the formation of a wall 90.

Because the end use of the panels 40 will oftentimes be known, eachpanel may be specifically constructed for that particular application.Therefore each panel 40 may be custom formed and include optionalfeatures that may be advantageously utilized in the building's 77construction. One such feature that has been identified as a commonlydesired option is the provision of an elongate recess 75 along a portionof the panel 40 that will be horizontally located at a distance abovethe flooring of a building 77. This recess 75 is configured and sized sothat it accepts different conduits that may be desired to be run withinan upright wall 90 of the building 77. In this configuration, when thepanel 40 is installed into a building 77, the elongate recess 75 will besubstantially parallely oriented to a bottom edge or base 95 of the wall90 at a distance of approximately fourteen inches from that edge 95.

Another embodiment of the present invention is the utilization of theabove described lightweight concrete panel 40 in the construction of abuilding 77 as described herein. In this embodiment of the invention,the several lightweight concrete panels 40 required for the building's77 construction are made at a manufacturing facility that is oftentimesremotely located from the actual building site. At the site, a buildingfoundation 80 serves as the base upon which the balance of the buildingis constructed. In that construction, the several concrete panels 40 areerected upon the foundation 80 in an upright or up-ended orientation.Prior to such erection, the foundation 80 is framed and poured so thatthe resulting configuration is ready for acceptance of the severalpanels 40 to be erected thereon. To facilitate the installation of suchpanels 40, a recess 85 is established about a perimeter of thefoundation 80 for receiving the base or lower end 95 of an upright panel40 forming an exterior wall 90 of the building 77. In a preferredembodiment, the recess 85 is established by placing a three by four inchor similarly configured metal angle 97 at the top exterior edges of thefoundation 80. Such angles are oriented so that they open outwardly awayfrom the interior portions of the foundation 80 and provide a seat 97for the base 95 of the up-righted panels 40.

The depth at which such angles 97 are recessed into the foundation 80 issuch that in a preferred embodiment, the exterior surface of the uprightpanel 40 is aligned and substantially planar to the exterior surface ofthe foundation 80 located and extending below the upright wall 90. Inthis manner, a substantially continuous side wall of the building 77 isestablished and may be appropriately treated for weather resistance andother desirable qualities. In this configuration, the elongate recess 75that had been created within the panel 40 during its manufacture isdirected inwardly so that any conduits located therein will be protectedfrom environmental elements and retained substantially within the bodyof the panel 40 itself. As previously described, the thickness of suchwalls may be varied according to specifications by changing thethickness of the panels 40 utilized in the construction.

It is also contemplated that the lightweight concrete panel 40 may beutilized as interior upright walls 90 that may be directly positionedand located upon an upper surface of the building foundation 80 or maybe optionally recessed into the top surface of the foundation 80. It iscontemplated that such a recess may be established by the location of anappropriately sized C-shaped purlin 65 located within the body of thefoundation with its opening even with the upper foundation surface.

The angle iron 97 with which the recess 85 is established within thefoundation 80 is contemplated to be advantageously constructed frommaterials that may be compatibly connected directly to the frame 50located about the perimeter of the panels 40. That is to say, it ispreferred that the frame segments 45 be constructed from a compatiblemetal to the angle iron 97 so that the bases 95 of the upright walls 90may be welded within the recess 85. Alternatively, adhesives of varioustypes may be similarly utilized, but welding is appreciated for itsstrength and integrity in the building industry. Accordingly, suchpanels 40 are erected upon the foundation 80 thereby establishingupright walls 90; adjacent panels 40 may be connected one to the otherto provide a fortifying strength to the building 77 itself. As with theconstruction and connection between the base of the panel 95 and therecess 85, it is preferred that the attachment of adjacent panels be bywelding between appropriately constructed panel frames 50.

Because of each panel's 40 ability to support and withstand substantialcompression forces applied thereto, such walls 90 may be used as weightbearing construction components in contrast to conventionallyconstructed non-load bearing walls comprising such materials assheetrock and plywood. Walls constructed according to the presentinvention from lightweight concrete panels 40 may have roofingstructures supported thereon, or even upper-floor slabs.

In keeping with the utilization of the herein described lightweightconcrete mixture 10, it is contemplated that the upper floors describedimmediately above may also be formed from the lightweight concretemixture 10. This concrete construction may be employed where nototherwise feasible because of the substantial reduction in weight madepossible by the polystyrene pellets 25 entrained within the mixture 10.Furthermore, the use of the lightweight concrete mixture 10 adds fireretardation qualities, as well as temperature insolation and sounddeadening capabilities.

Ultimately, because of the enhanced features of appropriatelyconstructed panels 40 that enable the panels 40 to be sawed, nailed, andotherwise manipulated, it is possible to finish the construction of thebuilding 77, both interiorly and exteriorly with conventional anddesired materials. Still further, it is contemplated that buildings 77may be constructed from continuous panels 40 that are then provided withapertures for accommodating such structural features as doors, windowsand other passages. Alternatively, the panels may be formed having suchapertures already constructed therein. The ability to establish suchfeatures on-site, however, is highly desirable and eliminates theinclusion of pre-erection and design requirements at the manufacturingfacility. In this way, uniform panels may be utilized that are lessexpensively and more time efficiently constructed and handled throughoutthe manufacturing process, as well as during erection at the buildingsite. After a building 77 has been constructed as described, a roofingsystem may be applied directly thereto and supported upon such wallstructures.

An additional embodiment of the present invention illustrated in FIG. 8contemplates the utilization of the lightweight concrete mixture 10 inthe manufacture of large sized building block units 200 that may be usedas substitutes for conventionally known cinder blocks in theconstruction of buildings 77. Because of the substantially reducedweight of these newly configured blocks 200, they may be substantiallylarger than known cinder blocks. Their configuration, however, issimilar in that alignable voids or hollowed columns 205 are included sothat when several blocks are stacked and staggered one row upon theother they may be tied together through these aligned columns 205 bysuch means as rebar 210. Later a load bearing columns are constructed bythe filing of such aligned voids with either lightweight concrete 10 orconventional concrete mixtures. Like the panels 40, it is contemplatedthat blocks 200 accordingly constructed may be remotely manufacturedfrom the building site. Because these blocks have such a reduced overallweight, installation personnel may individually lift into position eachblock 200, even when having lengths exceeding three feet. In otherrespects, the walls resulting from such blocked construction may befinished similar to those constructed from the lightweight concretepanels 40.

The building block units 200 may be glued together between increasinglyrising layers as opposed to using conventional mortar known from cinderblock construction. By eliminating the use of mortar between layers,there is no longer a concern about a squeeze effect that displacesmortar between lower layers of blocks as a result of the increasinglayers of blocks stacked thereupon. In a preferred embodiment, the firstrow of blocks 200 may be glued directly to a supporting foundation withincreasing rows glued thereupon as they are stacked one above the other.In conventional construction using cinder blocks, only a prescribednumber of rows of blocks could be installed at one time. This limitationhas been eliminated by substituting the glue for mortar which permits anentire wall to be continuously stacked without concern for the increasedweight caused by the building block units 200.

An enhanced version of the concrete panel 40 whose construction isdescribed herein above has been discovered wherein a composite laminate100 is applied to at least one exterior surface of a panel 140. Thecomposite laminate 100 is formed into a layer substantially covering atleast one side surface of the panel 140. This laminate 100 isconstructed from a resin based material in at least one embodiment. Inthis embodiment, multiple layers establishing the composite areinstalled one upon the others. Initially, a first layer of a catalyzedresin 105 is brush painted, sprayed or otherwise applied in a layer uponone of the side surfaces of a panel 140. To that first layer, a layer offiberglass cloth or mat 110 is applied that continuously covers the sidesurface of the panel 140. In a preferred embodiment, this fiberglasscloth 110 is seven ounce mesh. This two layer composite 100 can then berepeated multiple times thereby forming a laminate of variable thicknessand strength.

One particular environment wherein this composite laminate has beenutilized is for repelling flying missiles. Such missiles are oftenencountered in storm situations such as tornadoes and hurricanes. Inthese cases, building code provisions will often call for a specificrepelling capability that may be measured in a wall's ability to stop amissile of a specified weight and traveling at a certain speed frompenetrating the wall. One specific example and test is outlined hereinbelow regarding such a composite laminate 100 upon the side surface of apanel 140.

It is also contemplated that this composite laminate 100 can be added tothe building block construction described herein above. Still further,such a laminate can be added directly to roofing materials that haveholes or voids extending therethrough to affect an impact resistantsealer by providing a continuous waterproof coating thereto.

Another example of suitable mesh 110 is the high strength material knownby the trade name the aramid resin sold by E. I. Du Pont de Nemours andCompany under the trademark KEVLAR. As illustrated in FIG. 7, a typicalconcrete panel 140 may be constructed within the frame 150 about thepanel's 140 perimeter. Within the body of the panel is located anexpanded steel sheet which in the preferred embodiment is shown as awebbed sheet 160. This sheeting 160 is fixed within the frame 150 aboutthe sheets 160 periphery. Either lightweight concrete 10 is then pouredabout the expanded steel sheeting 160, or if end use requirementsdictate, standard andlor high density concrete may be used for theencasement about the steel sheeting 160 thereby establishing the body ofthe panel 140. The composite laminate 100 is then added as either acoating or adhered layer to at least one of the side surfaces of thepanel 140. Alternatively, it is contemplated that the composite layer100 may be placed within the interior of the panel 140, but it is mostadvantageously placed at the exterior surface.

By the layered panel construction described immediately above, it hasbeen discovered that the resulting concrete panel 140 has especiallyhigh capacities for resisting side loads upon the panel 140, andespecially impact loads resulting from objects striking thereupon. Anexample would be airborne objects carried by the high winds of a tornadoor hurricane. As will be demonstrated below, these types of strikingforces can be recreated in test facilities and controlled to determinethe capabilities of panels 140 so constructed.

Through the inclusion of the laminate layer, it has been discovered thatgreat impact forces can be resisted and the integrity of the concretepanel 140 preserved. Not only does the high strength laminate layer 100resist breakage upon impact from a striking object, but it also servesto spread and distribute the force over the surface of the panel 140 sothat high stresses or point stresses are not experienced in the body ofthe panel 140. It has also been discovered that such a laminate layercan serve as the waterproofing that imparts the advantageouscharacteristics for the panel 40 described hereinabove with respect towater-shed characteristics in subterranean settings.

The combination of the concrete panel 140 together with the laminatelayer 100 has withstood striking forces with surprising results. Atleast one panel constructed as illustrated in FIG. 7 and describedherein above has been tested with successful results under stormconditions. These conditions and the results of that test are describedherein below.

TEST RESULT

A missile impact test was performed on a prefabricated lightweightconcrete panel 140 constructed as described herein above, including theresistive laminate layer. The panel 140 had a height and width of fourfeet and a thickness of four inches. A four inch steel channel section165 extended around the perimeter of the test panel 140. The face of thepanel 140 was coated with a composite laminate 100 similar to the aramidresin sold by E. I. Du Pont de Nemours and Company under the trademarkKEVLAR. The objective of this test was to qualify the test panel 140 fortornado missile impact criteria. One missile impact test was performedon the panel 140. The panel 140 was tested on Apr. 21, 1997. Thedesignated missile did not perforate. The panel 140 was successful inresisting the prescribed missile impact.

The missile impact test facility in the Civil Engineering Department atTexas Tech University, Lubbock, Tex., was used to conduct the tests. Thetornado missile cannon was used to propel the missile. The cannon is airactuated and capable of propelling two inch by four inch timber missilesat speeds in excess of 150 miles per hour. A calibrated electronictiming device measures the speed of the missile just prior to impact. Areaction frame supported the test panel 140; a backstop controls themissile if it perforates the test panel 140.

The panel was tested against tornado missile criteria of the FederalEmergency Management Agency (FEMA), TRS-83A, Interim Guidelines forBuilding Occupant Protection from Tornadoes and Extreme Winds (1980).The criteria calls for a two inch by four inch timber missile weighingfifteen pounds and striking on end with an impact speed of 100 mph. Theactual missile used was a two inch by four inch timber weighing fourteenand seven tenths of a pound and having a length of twelve feet. The testpanel 140 was clamped to the reaction frame with C-clamps. A plasticsabot was attached to the trailing end of the missile prior to insertingthe missile into the cannon barrel. The operational air pressure was setat 43.0 psi to obtain a missile speed of 102 mph to compensate for the0.3 lb. under weight.

The test panel 140 was impacted with the two inch by four inch timbermissile at an impact speed of 124.1 miles per hour. The impact point wasnear the center of the panel 140. The missile perforated the compositecoating on the front face, but did not penetrate or perforate the panel140. In fact, the missile broke up into splinters.

A lightweight concrete composition and several of its specialapplications have been described herein. An exemplary application is thecombination of a concrete building construction panel with a compositelaminate coating or composite layer that fortifies and sufficientlystrengthens the combined panel to a degree that a panel so constructedcan be used for construction purposes in high strength storm areas.These and other variations which will be appreciated by those skilled inthe art are within the intended scope of this invention as claimedbelow. As previously stated, detailed embodiments of the presentinvention are disclosed herein; however, it is to be understood that thedisclosed embodiments are merely exemplary of the invention that may beembodied in various forms.

INDUSTRIAL APPLICABILITY

The present invention finds industrial applicability in its utilizationin building component units. More specifically, the lightweight concretemixture may be utilized in the manufacture of concrete panels to be usedas interior and exterior walls and flooring and roofing panels. Thelightweight concrete may also be used in the construction of buildingblocks used as substitute for conventional cinder block construction.Further, the concrete panels may be coated by a composite laminate forthe prevention of the penetration or perforation of the panel by amissle such as occurs during a tornado.

What is claimed is:
 1. A method of manufacturing a projectile resistantconcrete panel used in the construction of buildings and configured toresist damage caused by side impacts from wind-blown objects duringsevere storm conditions, said method comprising the stepsof:establishing a concrete panel for use in the construction of abuilding; applying a composite laminate to at least one exterior surfaceof said panel for establishing a projectile resistant panel; andconfiguring said Projectile resistant panel to retard piercings by awind-blown object wherein said wind-blown object is a two inch by fourinch timber missile weighing fifteen pounds and striking on end with animpact speed of at least one hundred miles per hour.
 2. The method ofmanufacturing a concrete panel as recited in claim 1 wherein saidlaminate establishes a sufficient thickness upon said layer to create apanel capable of resisting penetration by a missle.
 3. The method ofmanufacturing a concrete panel as recited in claim 1 wherein the methodof making said panel is further comprised of the steps of:coupling aplurality of frame segments so that a concrete frame is established,said frame having an interior space for receiving a concrete mixture;filling said frame with said concrete mixture so that said interiorspace is spanned by said concrete mixture across said frame therebycreating a panel; and curing said concrete mixture to a rigid state sothat said concrete mixture is retained within said frame thereby forminga lightweight concrete panel.
 4. The method of manufacturing a concretepanel as recited in claim 3 wherein said concrete mixture is alightweight concrete mixture.
 5. The method of manufacturing concretepanels as recited in claim 4 further comprising:preparing saidlightweight concrete mixture by mixing a slurry having water, acementing binder and a fine grain aggregate and add-mixing polystyrenepellets to said slury thereby forming a substantially homogeneouslightweight concrete mixture, said polystyrene pellets comprising agas-filled cellular interior encased within an exterior skin, saidexterior skin being substantially impervious to said slurry.
 6. Themethod of manufacturing concrete panels as recited in claim 1 whereinsaid composite laminate is comprised of a catalyzed resin.
 7. The methodof manufacturing concrete panels as recited in claim 6 wherein saidcomposite laminate is further comprised of a mat.
 8. The method ofmanufacturing concrete panels as recited in claim 7 furthercomprising:constructing said composite laminate by applying at least onelayer of said resin upon at least one side surface of said panelsubstantially covering said side surface of said panel; applying saidmat to said resin wherein said mat continuously covers said side surfaceof said panel; and increasing the thickness and strength of saidlaminate by repeating the process of applying layers of said resin andsaid mat to said panel.
 9. The method of manufacturing concrete panelsas recited in claim 8 wherein said thickness and strength of saidlaminate is such that said concrete panel is able to resist impact of ofa missle having a speed upon impact of at least one hundred miles perhour, said missle having dimensions of two inches by four inches bytwelve feet and weighing fourteen and seven tenths of a pound.
 10. Themethod of manufacturing a projectile resistant concrete panel used inthe construction of buildings and configured to resist damage caused byside impacts from wind-blown objects during severe storm conditions asrecited in claim 1, further comprising:testing the storm worthiness ofsaid projectile resistant concrete panel by projecting a two inch byfour inch timber missile weighing fifteen pounds toward said projectileresistant concrete panel; and striking said projectile resistantconcrete panel with said timber missile on end with an impact speed ofat least one hundred miles per hour.
 11. The method of manufacturing aprojectile resistant concrete panel used in the construction ofbuildings and configured to resist damage caused by side impacts fromwind-blown objects during severe storm conditions as recited in claim10, wherein said impact speed exceeds one hundred and twenty miles perhour and penetration of said projectile resistant concrete panel isretarded.
 12. The method of manufacturing a projectile resistantconcrete panel used in the construction of buildings and configured toresist damage caused by side impacts from wind-blown objects duringsevere storm conditions as recited in claim 10, furthercomprising:directing said timber missile toward a center of saidprojectile resistant concrete panel; and impacting said projectileresistant concrete panel at a substantial geometric center thereof. 13.A projectile resistant concrete panel for use in the construction ofbuildings comprised of:a projectile resistant concrete panel; acomposite laminate that covers at least a portion of one side surface ofsaid panel thereby establishing a projectile resistant panel; and saidprojectile resistant panel adapted to retard piercings by a wind-blownobject wherein said wind-blown object is a two inch by four inch timbermissile weighing fifteen pounds and striking on end with an impact speedof at least one hundred miles per hour.
 14. The concrete panel asclaimed in claim 13 wherein said concrete panel is constructed bycoupling a plurality of frame segments so that a concrete frame isestablished, said frame having an interior space for receiving aconcrete mixture, filling said frame with said mixture so that saidinterior space is spanned by said concrete mixture across said frame,and curing said concrete mixture to a rigid state so that said concretemixture is retained within said frame thereby forming a concrete panel.15. The concrete panel as claimed in claim 13 wherein said concretemixture is a lightweight concrete mixture.
 16. The concrete panel asclaimed in claim 15 wherein said lightweight concrete mixture is furthercomprised of:a slurry having water, a cementing binder and a fine grainaggregate; and a plurality of polystyrene pellets, wherein said pelletsare add-mixed to said slurry thereby forming a substantially homogeneouslightweight concrete mixture, said polystyrene pellets comprising agas-filled cellular interior encased within an exterior skin, saidexterior skin being substantially impervious to said slurry.
 17. Theconcrete panel as claimed in claim 13 wherein said laminate is furthercomprised of at least one layer of a catalyzed resin applied to saidside surface of said panel.
 18. The concrete panel as claimed in claim17 wherein said laminate is further comprised of at least one layer of amat applied to said resin.
 19. The concrete panel as claimed in claim 18wherein said laminate is of sufficient thickness and strength to createa panel capable of resisting penetration by a missle.